Frequency-Agile Distributed-Sensor System (FADSS) Deployment in the Western United States: VLF Results
|
|
- Spencer Robinson
- 5 years ago
- Views:
Transcription
1 Frequency-Agile Distributed-Sensor System (FADSS) Deployment in the Western United States: VLF Results ABSTRACT D. D. Rice, J. V. Eccles, J. J. Sojka, J. W. Raitt, Space Environment Corporation 221 N. Spring Creek Parkway, Suite A, Providence UT R. D. Hunsucker, R P Consultants, 7917 Gearhart Street Klamath Falls, OR A network of inexpensive, frequency-agile, beacon monitors is currently being developed to provide a real-time description of space weather effects on ionospherically-dependent systems. This array of software radios is dynamically programmed to measure GPS variations and received signal strengths from select beacons from VLF through HF along a multitude of propagation paths. The real-time network collects the information and augments it with geophysical data (GOES, various indices.) Processing provides information on the prevailing ionospheric weather conditions, and allows the scheduling of sensor observations to be optimized. We describe the VLF signal strength results of our initial six-station deployment. The initial FADSS frequency selection includes Navy VLF stations in Washington, North Dakota, Hawaii, and Maine. The sensors are deployed in the Western United States: KFO (Klamath Falls, Oregon), BLO (Bear Lake Observatory, Utah), PRV (River Heights, Utah), LGN (Logan, Utah), TUC (Tucson, Arizona), and SEC (at SEC office in Providence, Utah.) Additional beacon monitors are being fabricated for temporary observing campaigns. In this study these measurements are augmented by almost two years of monitoring from Providence, Utah by receivers of the Stanford IHY program. The data show strong seasonal effects on the D-region during solar minimum conditions. In summer, daytime signal levels are quite constant except during Sudden Ionospheric Disturbances (SIDs) related to solar x-ray flares. At night, signal levels are highly variable with gravity wave periods of 1-2 hours dominating. In winter, daytime VLF signal strengths are modulated with periods consistent with planetary waves of several days to more than a week. This modulation also affects signals at low HF frequencies through D-region absorption. The multi-point FADSS measurements are used to deduce the scale lengths of the D-region structures. This information is used to improve ionospheric specification as well as generate knowledge on the scale sizes of these space weather-related ionospheric structures. 1. INTRODUCTION A frequency-agile distributed-sensor system (FADSS) consisting of inexpensive radio beacon monitors is being developed to evaluate propagation conditions from VLF through HF and infer space weather effects. Each monitor is based on a software receiver covering 9 khz to 30 MHz, equipped with a compact active antenna. A GPS receiver provides accurate time and location information, and may provide additional data about ionospheric disturbances through analysis of reported position variations for a fixed location. A typical beacon monitor is shown in Figure 1. The monitoring system consists of a network distributed across Utah, Oregon, and Arizona (Figure 2) with additional units that can be set up in other locations for observing campaigns. Receivers were deployed between September and November 2007; their coordinates are listed in 1
2 Table 1. There are also two fixed-frequency VLF receivers operated by Utah State University in the Providence, Utah area that are part of the Stanford International Heliospheric Year (IHY) SID project. Those receivers provided initial VLF observations during the design phase of the present study, and continue to provide supplementary observations. Numerous studies of VLF propagation have been carried out over the years, but most have focused on long paths of several thousand kilometers. Long paths tend to average out smaller-scale ionospheric weather effects, allowing large-scale behavior such as solar flare impacts to be studied. The purpose of this project is to study the smaller-scale effects (e.g., gravity waves, absorption anomalies) and to characterize specific geographical sections of the ionosphere. Thus we emphasize short signal paths, less than about 2000 km. Figure 1. Typical beacon monitor consisting of a Linux PC with a PCI-based software radio installed. The GPS receiver is sitting on the PC case, and the wideband active antenna is leaning against the PC. The GPS receiver and active antenna are installed outdoors at roof level when the monitor is deployed. TABLE 1. Primary beacon monitoring locations. Receiver Location North Latitude East Longitude Altitude, m BLO Bear Lake Observatory, UT KFO Klamath Falls, Oregon LGN Logan, Utah PRV River Heights, Utah SEC Providence, Utah TUC Tucson, Arizona
3 Figure 2. Observational network completed in November 2007 showing northern Utah (left) and the southwestern US (right.) Shaded areas are populated regions. The cluster of systems in the Logan/Providence area is used for development and testing. The primary VLF transmitters monitored for this project are NML (25.2 khz) in La Moure, North Dakota and NLK (24.8 khz) in Jim Creek, Washington. These transmitters provide the relatively short paths to the receivers. Longer paths to NAA (24.0 khz) in Cutler, Maine and NPM (21.4 khz) in Lualualei, Hawaii are also monitored, since they may help characterize large-scale phenomena. The paths are shown in Figure 3, and distances between the VLF transmitters and receivers are shown in Table 2. Two HF transmitters, WWV and WWVH, are shown in Figure 3 and are also monitored as part of this project, and HF signal absorption is used as another diagnostic of D-region density. In addition, monitoring of NAU (40.8 khz) in Puerto Rico and WWVB (60 khz) in Fort Collins is planned for the near future. Besides providing additional signal paths, NAU and WWVB are in the LF range and should exhibit different propagation characteristics than the currently-monitored VLF signals. TABLE 2. Distances between receivers and VLF transmitters in km. Receiver NAA 24.0 khz NLK 24.8 khz NML 25.2 khz NPM 21.4 khz BLO KFO LGN PRV SEC TUC SEASONAL VARIATIONS IN VLF SIGNALS For path lengths of less than 2000 km, diurnal and seasonal variations in VLF signal strength are quite sensitive to the path length. The signal strength for a given path depends on the effective reflection height H of the earth-ionosphere waveguide, and analysis of H variations with the Long Wave Propagation Capability (LWPC) [Ferguson, 1998] shows that certain combinations of H and sharpness β produce signal strength minima and maxima for the path. 3
4 Figure 3. VLF transmitter/receiver paths that are currently monitored. WWV/WWVH HF transmissions are also monitored for this project. The complete 2007 VLF data set of the NML to PRV path obtained from the Stanford IHY SID receiver is shown in Figure 4. The signal strength is shown as a function of UT and day of year. The very distinctive hourglass shape is due to the seasonal variation of daylight hours. The area inside the hourglass shape is nighttime, where maximum signal levels are usually observed. The narrowest section of the hourglass is summer solstice. The bottom of the hourglass is January, and the top is December. The series of regularly-spaced black horizontal stripes between 1200 and approximately 2000 UT represent once-per-week maintenance outages of the NML transmitter. White areas are missing data caused by failures at the receiver site. For the NML-PRV path, LWPC shows a well-defined signal strength minimum associated with H ~ 84 km for normal ranges of β. Daytime H values are ~72 km, and nighttime values are ~90 km. Thus at dawn and dusk, H passes through the minimum signal region, producing the sharp border of the hourglass shape. The dawn crossing (right side) is sharper than the dusk crossing, and is sharpest in summer. This behavior is consistent with the solar zenith angle changing more rapidly during summer dawn than during winter dawn. The dusk crossing is indistinct at times during the winter, suggesting that the β value is large enough at dusk to prevent the significant signal minimum from occurring. Some seasonal effects in Figure 4 have less obvious causes. Daytime signal levels increase abruptly in mid-april and decrease again in October. A gradual shift between winter and summer signal levels is expected due to higher summer sun angles, but the abrupt change suggests that another cause, such as a seasonal change in mesospheric wind patterns. The nighttime signal levels reach much higher levels in the summer, but also have much greater variability, with nighttime signals erratically dropping below daytime levels. The greater summertime variability could be due to H being lower in summer than in winter, near the very sensitive range of H ~84 km where the signal strength minimum occurs on the NML-PRV path. For a summer H ~87 km, vertical 4
5 motions due to winds and waves would produce larger signal variations than for a winter H of 90 km. Figure 4. Signal strength observations for 2007 from the Stanford NML receiver in Providence, Utah. Again, the behavior shown in Figure 4 is specific to the NML-PRV path. The seasonal behavior is actually quite similar in the NLK-PRV data, which has a similar path length, but diurnal signal changes in KFO and TUC data are very different due to differing earth-ionosphere waveguide lengths and geometries. For example, the NLK-KFO data has a strong signal 5
6 enhancement at dawn and dusk rather than a minimum, while NML-KFO, NML-TUC, and NLK- TUC paths have very subtle changes in signal levels at dawn and dusk. 3. WEATHER VARIATIONS IN VLF SIGNALS The year 2007 shown in Figure 4 proved to be a particularly quiet solar minimum year, with few significant solar flares and modest geomagnetic activity. Close inspection of the daytime signal (outside of the hourglass) reveals the few sudden ionospheric disturbances (SIDs) that occurred as short stripes of enhanced signal; for example, two flare SIDs occurred on June 1. Figure 5 shows the signal strength as a function of UT hour at PRV for two transmitters on June 1, 2007, when two solar flares produced classic sudden ionospheric disturbance (SID) signatures. The two transmitters are NML (left) and NLK (right), located in North Dakota and Washington State respectively (Figure 3.) GOES x-ray solar data indicate that the 1500 UT flare was C9 class, and the 2150 UT flare was C8 class. Thomson et al [2005] have studied how the bottomside of the D-region is lowered depending on the class of the x-ray flare, and together with D-region physics models, a good estimate of the ionospheric response is available. For the NML- PRV path, the two SIDs have about the same amplitudes, while the first SID on the NLK-PRV path has a much lower amplitude than the second. The paths have different geometries, with the NLK- PRV path being 125 km shorter than the NML-PRV path, but the major difference between the two paths in this case is the solar zenith angle. A solar zenith angle dependence for the D-region bottomside has been found and quantified by McRae and Thomson [2000]. In this case, the first flare occurs earlier in the morning on the NLK-PRV path than on the NML-PRV path, and thus experiences a smaller x-ray enhancement. Figure 5. Signal strength in Providence Utah for NML (left) and NLK (right) showing sudden ionospheric disturbance (SID) signatures at 1500 and 2200 UT corresponding to solar x-ray flares. Another weather phenomenon visible in Figure 4 is bands of enhanced signal during the winter night (specifically from mid-october to December 2007) that are several days apart (compare with the weekly transmitter downtime stripes.) The timing of these enhancements is consistent with planetary wave periods, and may result from NO transport from higher latitudes associated with the waves [Kawahira, 1985]. Some of these night VLF enhancements correlate with daytime HF signal absorption (Figure 6), showing that the changes in the D-region persist through the day, and suggesting a connection to the winter absorption anomaly that has been observed at HF for decades. The VLF path is well northwest of the HF path, but on several occasions (25-27 December 2007, 31December-2 January 2008, 26 January-6 February 2008) nighttime VLF increases corresponded to daytime HF absorption. 6
7 A key question for FADSS is the geographic distribution and extent of ionospheric weather variations. For solar flare effects, the extent is assumed to be the entire dayside hemisphere, but for planetary wave-driven NO enhancements, studies of absorption suggest that scale sizes are less than 500 km [Schwentek, 1974]. Smaller scale variations on the order of tens to hundreds of kilometers are produced by atmospheric gravity waves; see Taylor et al. [2007] for examples of optical mesospheric gravity wave observations at BLO. It is hoped that analysis of the various paths in the FADSS, and the overlaps in the path data, will allow for a more detailed ionospheric specification that will provide new information about the scale sizes and distributions of D-region irregularities. Clearly, more sensors are needed, and short-term mobile campaigns are planned to collect data from various locations across the Western United States during the next year. -5 Klamath Falls Signal -10 Signal, db MHz Day NLK Night Month/Day, Figure 6. Comparison of average night VLF and day HF signal observed at KFO. Low HF signal levels reflect increased D region absorption CORRELATION SCALES OF VLF OBSERVATION The current FADSS deployment has two scales, shown in Figure 2: the cluster shown in the left panel of the figure and the wide-area network shown in the right panel. Comparing the signals from these receivers shows how the signals correlate over short ranges, and limiting the comparison to night (about UT for early January in Utah) eliminates differences in solar zenith angle along the paths. Nighttime signals from NML received by the cluster of receivers in the Logan, Utah area are shown in Figure 7. Data points are at three-minute intervals, and correlated variations are seen on various time scales, ranging from about 15 minutes through several hours. The BLO receiver shows the least correlation, and it is the farthest from the cluster (42 km from SEC.) The other receivers are within about 5 km of each other
8 NML, 5 Jan BLO LGN PRV SEC UT Hour Figure 7. Signal correlations between receivers in a 50 km-wide area. The correlated variations in Figure 7 have periods typical of atmospheric gravity waves and long-period inertial or tidal waves after 0600 UT. The 42 km distance between BLO and the other monitors is comparable to short-scale gravity wavelengths, and is about three signal wavelengths, so small differences between the received signal at BLO and the other monitors are reasonable. Differences between the LGN/PRV/SEC monitors are most likely due to local interference, variations in antenna characteristics, and system noise. Signals from NML to the three remote receivers at BLO (Utah), KFO (Oregon), and TUC (Arizona) are shown in Figure 8. While all three signals show wave-like variations, there is no obvious correlation between them. The paths are widely separated (see Figure 3) so there are differences in dawn and dusk times and potentially different weather conditions along the paths due to wind and wave effects. We would not generally expect obvious correlations between distant receivers. Even assuming a wide-area disturbance that affects the signal paths in the same way (such as a solar flare), the resulting signal fluctuations will have different signatures at different locations due to differing patterns of constructive and destructive interference between modes along the waveguide. Figure 9 illustrates this situation: an M2-class solar flare at 1900 produces a simple increase in signal on the NLK-PRV path, but produces an initial sharp decrease in signal on the NLK-KFO path followed by an increase. Ideally, these differences will be accounted for through the LWPC modeling analysis. Atmospheric waves will complicate the analysis, however, since wavelengths and directions of the waves are unknown, so the amplitude variation due to the atmospheric waves across the various signal paths is also unknown. It is hoped that waves with large amplitudes and wavelengths may be identified using multiple overlapping signal paths, but the optimal arrangement and spacing of signal paths remains to be determined. 8
9 NML, 5 Jan BLO KFO TUC UT Hour Figure 8. Signal correlations across the Western United States. Figure 9. SID from x-ray flare at 1900 UT observed in Klamath Falls (left) and Providence (right.) Dark vertical lines indicate local dawn and dusk. 5. CONCLUSIONS Long-term observations of fixed VLF transmitter-receiver signal paths can provide valuable information about weather in the D-region. Analysis of the signal data requires a suitable waveguide propagation model such as LWPC, and an ionospheric model that provides information about the expected quiet-time diurnal and seasonal variations. Once the baseline has been established for signals under quiet conditions, large perturbations in the signal may be mapped to ionospheric weather. This study has collected examples of various signal perturbations and is currently developing the analysis tools that will yield the ionospheric weather information. 9
10 The next step is to use the overlapping signal paths of the sensor network to estimate the location and extent of the inferred weather phenomena. A variety of signal paths will be examined with field campaigns during the next year. Data gathered so far have demonstrated connections between VLF propagation and HF absorption, and are being used to improve the AbbyNormal D-region model. Close examination of solar x-ray flare responses in these data sets have also suggested that assumptions about flare spectrum and D-region response will need to be revisited. In all, FADSS observations promise to make significant contributions to the understanding of D-region physics. Acknowledgement: This research was supported by SBIR II Contract FA C-0016 from AFRL at Hanscom AFB to the Space Environment Corporation. The assistance and support of Dr. Robert D. Hunsucker and Dr. John W. Raitt was essential to the success of this campaign. The VLF SID Space Weather Monitor is an instrument developed through a project sponsored by Stanford University, the National Science Foundation, NASA, and is part of the United Nations International Heliospherical Year, See for project information and data distribution. References Ferguson, K., Computer Programs for Assessment of Long-Wavelength Radio Communications, Version 2.0, Technical Document 3030, May 1998, Space and Naval Warfare Systems Center, San Diego, CA , Kawahira, K., The D region winter anomaly at high and middle latitudes induced by planetary waves, Radio Sci., 20, , McRae, W. M. and N. R.Thomson, VLF phase and amplitude: daytime ionospheric parameters, J. Atmos. Solar-Terr. Phys., 62, , Schwentek, H., Some results obtained from the European cooperation concerning studies of the winter anomaly in ionospheric absorption, COSPAR Proceedings of the Methods of Measurements and Results of Lower Ionosphere Structures Symposium held in Constance, F.R.G, edited by K. Rawer, , Taylor, M. J., W. R. Pendleton Jr., P-D. Pautet, Y. Zhao, C. Olsen, H. K. S. Babu, A. F. Medeiros, and H. Takahashi, Recent progress in mesospheric gravity wave studies using nightglow imaging system, Rev. Bras. Geof., 25(2), 49-58, doi: /S X , Thomson, N. R., C. J. Rodger, and M. A. Clilverd, Large solar flares and their ionospheric D- region enhancements, J. Geophys. Res., 110, A06306, doi: /2005ja011008,
Monitoring Solar flares by Radio Astronomy
Monitoring Solar flares by Radio Astronomy Presented at the RASC Sunshine Coast Centre, February 8th, 2013, 7:30 pm Mike Bradley, RASC Sunshine Coast Centre Solar flares Solar flares occur when sunspots
More informationAbstract. Introduction
Subionospheric VLF measurements of the effects of geomagnetic storms on the mid-latitude D-region W. B. Peter, M. Chevalier, and U. S. Inan Stanford University, 350 Serra Mall, Stanford, CA 94305 Abstract
More informationDaytime modelling of VLF radio waves over land and sea, comparison with data from DEMETER Satellite
Daytime modelling of VLF radio waves over land and sea, comparison with data from DEMETER Satellite S. G. Meyer 1,2, A. B. Collier 1,2, C. J. Rodger 3 1 SANSA Space Science, Hermanus, South Africa 2 School
More informationarxiv: v1 [astro-ph.ep] 23 Mar 2016
A study of VLF signals variations associated with the changes of ionization level in the D-region in consequence of solar conditions D.M. Šulića, V.A. Srećković b, A.A. Mihajlov b a University Union -
More informationFirst results of mapping sporadic E with a passive observing network
SPACE WEATHER, VOL. 9,, doi:10.1029/2011sw000678, 2011 First results of mapping sporadic E with a passive observing network D. D. Rice, 1 J. J. Sojka, 1 J. V. Eccles, 1 J. W. Raitt, 1 J. J. Brady, 1 and
More informationChapter 7 HF Propagation. Ionosphere Solar Effects Scatter and NVIS
Chapter 7 HF Propagation Ionosphere Solar Effects Scatter and NVIS Ionosphere and Layers Radio Waves Bent by the Ionosphere Daily variation of Ionosphere Layers Ionospheric Reflection Conduction by electrons
More informationMeasurement of VLF propagation perturbations during the January 4, 2011 Partial Solar Eclipse
Measurement of VLF propagation perturbations during the January 4, 2011 Partial Solar Eclipse by Lionel Loudet 1 January 2011 Contents Abstract...1 Introduction...1 Background...2 VLF Signal Propagation...2
More informationModelling the Ionosphere
The recent long period of solar inactivity was spectacularly terminated by a series of X-ray flares during January 2010. One of these, an M-class, produced an intense Sudden Ionospheric Disturbance (SID)
More informationSome studies of solar flare effects on the propagation of sferics and a transmitted signal
Indian Journal of Radio & Space Physics Vol. 38, October 2009, pp. 260-265 Some studies of solar flare effects on the propagation of sferics and a transmitted signal B K De 1, S S De 2,*, B Bandyopadhyay
More informationScientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and ElectroDynamics - Data Assimilation (IDED-DA) Model
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Scientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and ElectroDynamics - Data Assimilation
More informationChapter 6 Propagation
Chapter 6 Propagation Al Penney VO1NO Objectives To become familiar with: Classification of waves wrt propagation; Factors that affect radio wave propagation; and Propagation characteristics of Amateur
More informationSPACE WEATHER SIGNATURES ON VLF RADIO WAVES RECORDED IN BELGRADE
Publ. Astron. Obs. Belgrade No. 80 (2006), 191-195 Contributed paper SPACE WEATHER SIGNATURES ON VLF RADIO WAVES RECORDED IN BELGRADE DESANKA ŠULIĆ1, VLADIMIR ČADEŽ2, DAVORKA GRUBOR 3 and VIDA ŽIGMAN4
More informationVLF Data Acquisition and database storing
VLF Data Acquisition and database storing VLADIMIR A. SREĆKOVIĆ Institute of Physics, P.O.Box 57, Pregrevica 118, Belgrade, Serbia Brno, April 2016 Outline The collaborators (Short intro. about the work
More informationStudy of small scale plasma irregularities. Đorđe Stevanović
Study of small scale plasma irregularities in the ionosphere Đorđe Stevanović Overview 1. Global Navigation Satellite Systems 2. Space weather 3. Ionosphere and its effects 4. Case study a. Instruments
More informationDEVELOPMENT OF THE NEW ELF/VLF RECEIVER FOR DETECTING THE SUDDEN IONOSPHERIC DISTURBANCES
DEVELOPMENT OF THE NEW ELF/VLF RECEIVER FOR DETECTING THE SUDDEN IONOSPHERIC DISTURBANCES Le MINH TAN 1, Keyvan GHANBARI 2 1 Department of Physics, Faculty of Natural Science and Technology, Tay Nguyen
More informationStudy of solar flare induced D-region ionosphere changes using VLF amplitude observations at a low latitude site
Indian Journal of Radio & Space Physics Vol. 43, June 2014, pp 197-204 Study of solar flare induced D-region ionosphere changes using VLF amplitude observations at a low latitude site L M Tan 1,$,*, N
More informationA Study of the Effects of Sunrise and Sunset on the Ionosphere as Observed by VLF Wave Behavior
A Study of the Effects of Sunrise and Sunset on the Ionosphere as Observed by VLF Wave Behavior By Leandra Merola South Side High School Rockville Centre, New York Abstract The purpose of this study was
More informationNighttime Ionospheric D-region Parameters. from VLF Phase and Amplitude
Nighttime Ionospheric D-region Parameters from VLF Phase and Amplitude Neil R. Thomson, Mark A. Clilverd, and Wayne M. McRae Physics Department, University of Otago, Dunedin, New Zealand Physical Sciences
More informationAssimilation Ionosphere Model
Assimilation Ionosphere Model Robert W. Schunk Space Environment Corporation 399 North Main, Suite 325 Logan, UT 84321 phone: (435) 752-6567 fax: (435) 752-6687 email: schunk@spacenv.com Award #: N00014-98-C-0085
More informationNON-TYPICAL SERIES OF QUASI-PERIODIC VLF EMISSIONS
NON-TYPICAL SERIES OF QUASI-PERIODIC VLF EMISSIONS J. Manninen 1, N. Kleimenova 2, O. Kozyreva 2 1 Sodankylä Geophysical Observatory, Finland, e-mail: jyrki.manninen@sgo.fi; 2 Institute of Physics of the
More informationIntroduction To The Ionosphere
Introduction To The Ionosphere John Bosco Habarulema Radar School 12 13 September 2015, SANSA, What is a radar? This being a radar school... RAdio Detection And Ranging To determine the range, R, R=Ct/2,
More informationLarge Solar Flares and their Ionospheric D-region Enhancements
1 Large Solar Flares and their Ionospheric D-region Enhancements Neil R. Thomson and Craig J. Rodger Physics Department, University of Otago, Dunedin, New Zealand Mark A. Clilverd Physical Sciences Division,
More informationLow Latitude Ionospheric D-region Dependence on Solar Zenith Angle
1 1 2 3 Low Latitude Ionospheric D-region Dependence on Solar Zenith Angle Neil R. Thomson, 1 Mark A. Clilverd 2 and Craig J. Rodger 1 4 5 6 1 Physics Department, University of Otago, Dunedin, New Zealand.
More informationAWESOME for educational and research use
SuperSID - a small-version AWESOME for educational and research use By Deborah Scherrer Tim Huynh Stanford University Solar Center 1 What I am going to talk about What is this project? What can the instrument
More informationDaytime ionospheric D region sharpness derived from VLF radio atmospherics
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116,, doi:10.1029/2010ja016299, 2011 Daytime ionospheric D region sharpness derived from VLF radio atmospherics Feng Han, 1 Steven A. Cummer, 1 Jingbo Li, 1 and Gaopeng
More informationA study of the ionospheric effect on GBAS (Ground-Based Augmentation System) using the nation-wide GPS network data in Japan
A study of the ionospheric effect on GBAS (Ground-Based Augmentation System) using the nation-wide GPS network data in Japan Takayuki Yoshihara, Electronic Navigation Research Institute (ENRI) Naoki Fujii,
More informationSpace weather effects on midlatitude HF propagation paths: Observations and a data-driven D region model
Space weather effects on midlatitude HF propagation paths: Observations and a data-driven D region model J. V. Eccles Space Environment Corporation, Providence, Utah, USA R. D. Hunsucker RP Consultants,
More informationAnalysis of VLF Signals Perturbations on the Equatorial D-region Ionosphere Induced by Solar Flares
International Journal of Engineering & Technology IJET-IJENS Vol:1 No:3 14 Analysis of VLF Signals Perturbations on the Equatorial D-region Ionosphere Induced by Solar Flares Mohd Masri Abd Rashid, Mahamod
More informationHigh-frequency radio wave absorption in the D- region
Utah State University From the SelectedWorks of David Smith Spring 2017 High-frequency radio wave absorption in the D- region David Alan Smith, Utah State University This work is licensed under a Creative
More informationALTITUDE PROFILES OF ELECTRON DENSITY DURING LEP EVENTS FROM VLF MONITORING OF THE LOWER IONOSPHERE
The Sharjah-Stanford AWESOME VLF Workshop Sharjah, UAE, Feb 22-24, 2010. ALTITUDE PROFILES OF ELECTRON DENSITY DURING LEP EVENTS FROM VLF MONITORING OF THE LOWER IONOSPHERE Desanka Šulić 1 and Vladimir
More informationDETECTION OF TERRESTRIAL IONOSPHERIC PERTURBATIONS CAUSED BY DIFFERENT ASTROPHYSICAL PHENOMENA
Publ. Astron. Obs. Belgrade No. 96 (2017), 365-370 PhD Thesis DETECTION OF TERRESTRIAL IONOSPHERIC PERTURBATIONS CAUSED BY DIFFERENT ASTROPHYSICAL PHENOMENA A. NINA 1,V.M.ČADEŽ2,L.Č. POPOVIĆ2,V.A.SREĆKOVIĆ1
More informationGlobal Maps with Contoured Ionosphere Properties Some F-Layer Anomalies Revealed By Marcel H. De Canck, ON5AU. E Layer Critical Frequencies Maps
Global Maps with Contoured Ionosphere Properties Some F-Layer Anomalies Revealed By Marcel H. De Canck, ON5AU In this column, I shall handle some possibilities given by PROPLAB-PRO to have information
More information1. Introduction. 2. Materials and Methods
A Study On The Detection Of Solar Flares And Its Effects On The Daytime Fluctuation Of VLF Amplitude And Geomagnetic Variation Using A Signal Of 22.10 KHz Transmitted From England And Received At Kiel
More informationAssimilation Ionosphere Model
Assimilation Ionosphere Model Robert W. Schunk Space Environment Corporation 221 North Spring Creek Parkway, Suite A Providence, UT 84332 phone: (435) 752-6567 fax: (435) 752-6687 email: schunk@spacenv.com
More informationThe GPS measured SITEC caused by the very intense solar flare on July 14, 2000
Advances in Space Research 36 (2005) 2465 2469 www.elsevier.com/locate/asr The GPS measured SITEC caused by the very intense solar flare on July 14, 2000 Weixing Wan a, *, Libo Liu a, Hong Yuan b, Baiqi
More informationGround based measurements of ionospheric turbulence manifestations induced by the VLF transmitter ABSTRACT
Ground based measurements of ionospheric turbulence manifestations induced by the VLF transmitter Dmitry S. Kotik, 1 Fedor I. Vybornov, 1 Alexander V. Ryabov, 1 Alexander V. Pershin 1 and Vladimir A. Yashnov
More informationOn the generation mechanism of terminator times in subionospheric VLF/LF propagation and its possible application to seismogenic effects
Nat. Hazards Earth Syst. Sci., 8, 129 134, 28 www.nat-hazards-earth-syst-sci.net/8/129/28/ Author(s) 28. This work is licensed under a Creative Commons License. Natural Hazards and Earth System Sciences
More informationDaily and seasonal variations of TID parameters over the Antarctic Peninsula
Daily and seasonal variations of TID parameters over the Antarctic Peninsula A. Zalizovski 1, Y. Yampolski 1, V. Paznukhov 2, E. Mishin 3, A. Sopin 1 1. Institute of Radio Astronomy, National Academy of
More informationPoS(2nd MCCT -SKADS)003
The Earth's ionosphere: structure and composition. Dispersive effects, absorption and emission in EM wave propagation 1 Observatorio Astronómico Nacional Calle Alfonso XII, 3; E-28014 Madrid, Spain E-mail:
More informationNAVIGATION SYSTEMS PANEL (NSP) NSP Working Group meetings. Impact of ionospheric effects on SBAS L1 operations. Montreal, Canada, October, 2006
NAVIGATION SYSTEMS PANEL (NSP) NSP Working Group meetings Agenda Item 2b: Impact of ionospheric effects on SBAS L1 operations Montreal, Canada, October, 26 WORKING PAPER CHARACTERISATION OF IONOSPHERE
More informationSpatial and temporal extent of ionospheric anomalies during sudden stratospheric warmings in the daytime ionosphere
Spatial and temporal extent of ionospheric anomalies during sudden stratospheric warmings in the daytime ionosphere Larisa Goncharenko, Shunrong Zhang, Anthea Coster, Leonid Benkevitch, Massachusetts Institute
More informationChapter 1: Telecommunication Fundamentals
Chapter 1: Telecommunication Fundamentals Block Diagram of a communication system Noise n(t) m(t) Information (base-band signal) Signal Processing Carrier Circuits s(t) Transmission Medium r(t) Signal
More informationRadio Science, Volume 34, Number 4, Pages , July-August 1999
Radio Science Volume 34 Number 4 Pages 939-948 July-August 1999 Sunrise effects on VLF signals propagating over a long north-south path Mark A. Clilverd Neil R. Thomson and Craig J. Rodger British Antarctic
More informationRECOMMENDATION ITU-R P Prediction of sky-wave field strength at frequencies between about 150 and khz
Rec. ITU-R P.1147-2 1 RECOMMENDATION ITU-R P.1147-2 Prediction of sky-wave field strength at frequencies between about 150 and 1 700 khz (Question ITU-R 225/3) (1995-1999-2003) The ITU Radiocommunication
More informationDartmouth College SuperDARN Radars
Dartmouth College SuperDARN Radars Under the guidance of Thayer School professor Simon Shepherd, a pair of backscatter radars were constructed in the desert of central Oregon over the Summer and Fall of
More informationNVIS PROPAGATION THEORY AND PRACTICE
NVIS PROPAGATION THEORY AND PRACTICE Introduction Near-Vertical Incident Skywave (NVIS) propagation is a mode of HF operation that utilizes a high angle reflection off the ionosphere to fill in the gap
More informationResearch Letter Waveguide Parameters of 19.8 khz Signal Propagating over a Long Path
Research Letters in Physics Volume 29, Article ID 216373, 4 pages doi:1.1155/29/216373 Research Letter Waveguide Parameters of 19.8 khz Signal Propagating over a Long Path Sushil Kumar School of Engineering
More informationVLF REMOTE SENSING OF THE LOWER IONOSPHERE AND REAL TIME SIGNAL PROCESSING
VLF REMOTE SENSING OF THE LOWER IONOSPHERE AND REAL TIME SIGNAL PROCESSING VLADIMIR SREĆKOVIĆ 1, DARKO JEVREMOVIĆ 2, V. VUJČIĆ 2 1 INSTITUTE OF PHYSICS, P.O.BOX 57,UNIVERSITY OF BELGRADE 2 ASTRONOMICAL
More informationSatellite Navigation Science and Technology for Africa. 23 March - 9 April, The African Ionosphere
2025-28 Satellite Navigation Science and Technology for Africa 23 March - 9 April, 2009 The African Ionosphere Radicella Sandro Maria Abdus Salam Intern. Centre For Theoretical Physics Aeronomy and Radiopropagation
More information4/29/2012. General Class Element 3 Course Presentation. Radio Wave Propagation. Radio Wave Propagation. Radio Wave Propagation.
General Class Element 3 Course Presentation ti ELEMENT 3 SUB ELEMENTS General Licensing Class Subelement G3 3 Exam Questions, 3 Groups G1 Commission s Rules G2 Operating Procedures G3 G4 Amateur Radio
More informationChapter 2 Analysis of Polar Ionospheric Scintillation Characteristics Based on GPS Data
Chapter 2 Analysis of Polar Ionospheric Scintillation Characteristics Based on GPS Data Lijing Pan and Ping Yin Abstract Ionospheric scintillation is one of the important factors that affect the performance
More informationStudy of the Ionosphere Irregularities Caused by Space Weather Activity on the Base of GNSS Measurements
Study of the Ionosphere Irregularities Caused by Space Weather Activity on the Base of GNSS Measurements Iu. Cherniak 1, I. Zakharenkova 1,2, A. Krankowski 1 1 Space Radio Research Center,, University
More informationDetection and Characterization of Traveling Ionospheric Disturbances (TIDs) with GPS and HF sensors
Ionospheric Effects Symposium 12-14 May 2015 Alexandria, VA Detection and Characterization of Traveling Ionospheric Disturbances (TIDs) with GPS and HF sensors Keith Groves, Vadym Paznukhov, Eileen MacKenzie
More informationPrecursors of earthquakes in the line-of-sight propagation on VHF band
Precursors of earthquakes in the line-of-sight propagation on VHF band K. Motojima 1 1 Dept. Electronic Eng., Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, Gunma, Japan Abstract. This paper was intended
More informationVLF-LF PROPAGATION MEASUREMENTS DURING THE 11 AUGUST 1999 SOLAR ECLIPSE. R. Fleury, P. Lassudrie-Duchesne ABSTRACT INTRODUCTION EXPERIMENTAL RESULTS
VLF-LF PROPAGATON MEASUREMENTS DURNG THE 11 AUGUST 1999 SOLAR ECLPSE R. Fleury, P. Lassudrie-Duchesne Ecole Nationale Suptrieure des TClCcommunications de Bretagne, France ABSTRACT A survey of the VLF-LF
More informationMidlatitude daytime D region ionosphere variations measured from radio atmospherics
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115,, doi:10.1029/2010ja015715, 2010 Midlatitude daytime D region ionosphere variations measured from radio atmospherics Feng Han 1 and Steven A. Cummer 1 Received
More informationDiurnal Variation of VLF Radio Wave Signal Strength at 19.8 and 24 khz Received at Khatav India (16 o 46ʹN, 75 o 53ʹE)
Research & Reviews: Journal of Space Science & Technology ISSN: 2321-2837 (Online), ISSN: 2321-6506 V(Print) Volume 6, Issue 2 www.stmjournals.com Diurnal Variation of VLF Radio Wave Signal Strength at
More informationContinued Development and Validation of the USU GAIM Models
Continued Development and Validation of the USU GAIM Models Robert W. Schunk Center for Atmospheric and Space Sciences Utah State University Logan, Utah 84322-4405 phone: (435) 797-2978 fax: (435) 797-2992
More informationUnderstanding the unique equatorial electrodynamics in the African Sector
Understanding the unique equatorial electrodynamics in the African Sector Endawoke Yizengaw, Keith Groves, Tim Fuller-Rowell, Anthea Coster Science Background Satellite observations (see Figure 1) show
More information1. Terrestrial propagation
Rec. ITU-R P.844-1 1 RECOMMENDATION ITU-R P.844-1 * IONOSPHERIC FACTORS AFFECTING FREQUENCY SHARING IN THE VHF AND UHF BANDS (30 MHz-3 GHz) (Question ITU-R 218/3) (1992-1994) Rec. ITU-R PI.844-1 The ITU
More information[titlelscientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and Electrodynamics-Data Assimilation (IDED-DA) Model
[titlelscientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and Electrodynamics-Data Assimilation (IDED-DA) Model [awardnumberl]n00014-13-l-0267 [awardnumber2] [awardnumbermore]
More informationObservations of Ionosphere/Troposphere Coupling as Observed by COSMIC
Observations of Ionosphere/Troposphere Coupling as Observed by COSMIC K. F. Dymond, C. Coker, D. E. Siskind, A. C. Nicholas, S. A. Budzien, S. E. McDonald, and C. E. Dymond * Space Science Division, Naval
More informationAzimuthal dependence of VLF propagation
JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 1 5, doi:.0/jgra.533, 013 Azimuthal dependence of VLF propagation M. L. Hutchins, 1 Abram R. Jacobson, 1 Robert H. Holzworth, 1 and James B. Brundell
More informationStorms in Earth s ionosphere
Storms in Earth s ionosphere Archana Bhattacharyya Indian Institute of Geomagnetism IISF 2017, WSE Conclave; Anna University, Chennai Earth s Ionosphere Ionosphere is the region of the atmosphere in which
More informationThe Significance of GNSS for Radio Science
Space Weather Effects on the Wide Area Augmentation System (WAAS) The Significance of GNSS for Radio Science Patricia H. Doherty Vice Chair, Commission G International Union of Radio Science www.ursi.org
More informationThe Ionosphere and its Impact on Communications and Navigation. Tim Fuller-Rowell NOAA Space Environment Center and CIRES, University of Colorado
The Ionosphere and its Impact on Communications and Navigation Tim Fuller-Rowell NOAA Space Environment Center and CIRES, University of Colorado Customers for Ionospheric Information High Frequency (HF)
More informationVicki Hsu University of Colorado at Boulder MIT Haystack Observatory REU Program 2010 August 5, 2010
Vicki Hsu University of Colorado at Boulder MIT Haystack Observatory REU Program 2010 August 5, 2010 Motivation Ionospheric variability affects a variety of communication and navigation systems The current
More informationStudy of Ionospheric Perturbations during Strong Seismic Activity by Correlation Technique using NmF2 Data
Research Journal of Recent Sciences Res.J.Recent Sci. Study of Ionospheric Perturbations during Strong Seismic Activity by Correlation Technique using NmF2 Data Abstract Gwal A.K., Jain Santosh, Panda
More informationEFFECTS OF SCINTILLATIONS IN GNSS OPERATION
- - EFFECTS OF SCINTILLATIONS IN GNSS OPERATION Y. Béniguel, J-P Adam IEEA, Courbevoie, France - 2 -. Introduction At altitudes above about 8 km, molecular and atomic constituents of the Earth s atmosphere
More informationHIGH-FREQUENCY ACOUSTIC PROPAGATION IN THE PRESENCE OF OCEANOGRAPHIC VARIABILITY
HIGH-FREQUENCY ACOUSTIC PROPAGATION IN THE PRESENCE OF OCEANOGRAPHIC VARIABILITY M. BADIEY, K. WONG, AND L. LENAIN College of Marine Studies, University of Delaware Newark DE 19716, USA E-mail: Badiey@udel.edu
More informationRADIO SCIENCE, VOL. 42, RS4005, doi: /2006rs003611, 2007
Click Here for Full Article RADIO SCIENCE, VOL. 42,, doi:10.1029/2006rs003611, 2007 Effect of geomagnetic activity on the channel scattering functions of HF signals propagating in the region of the midlatitude
More informationDynasonde measurements advance understanding of the thermosphereionosphere
Dynasonde measurements advance understanding of the thermosphereionosphere dynamics Nikolay Zabotin 1 with contributions from Oleg Godin 2, Catalin Negrea 1,4, Terence Bullett 3,5, Liudmila Zabotina 1
More informationSpace Weather and the Ionosphere
Dynamic Positioning Conference October 17-18, 2000 Sensors Space Weather and the Ionosphere Grant Marshall Trimble Navigation, Inc. Note: Use the Page Down key to view this presentation correctly Space
More informationVI. Signal Propagation Effects. Image courtesy of
VI. Signal Propagation Effects Image courtesy of www.tpub.com 56 VI. Signal Propagation Effects Name Date Class At Home Assignment Tune to the most remote AM station you can find. You should attempt to
More informationPlasma effects on transionospheric propagation of radio waves II
Plasma effects on transionospheric propagation of radio waves II R. Leitinger General remarks Reminder on (transionospheric) wave propagation Reminder of propagation effects GPS as a data source Some electron
More informationIonospheric Impacts on UHF Space Surveillance. James C. Jones Darvy Ceron-Gomez Dr. Gregory P. Richards Northrop Grumman
Ionospheric Impacts on UHF Space Surveillance James C. Jones Darvy Ceron-Gomez Dr. Gregory P. Richards Northrop Grumman CONFERENCE PAPER Earth s atmosphere contains regions of ionized plasma caused by
More informationModeling a large solar proton event in the southern polar atmosphere
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110,, doi:10.1029/2004ja010922, 2005 Modeling a large solar proton event in the southern polar atmosphere Mark A. Clilverd, 1 Craig J. Rodger, 2 Thomas Ulich, 3 Annika
More informationIf maximum electron density in a layer is less than n', the wave will penetrate the layer
UNIT-7 1. Briefly the describe the terms related to the sky wave propagation: virtual heights, critical frequency, maximum usable frequency, skip distance and fading? Ans: Sky wave propagation: It is also
More informationIonospheric Imprint to LOFAR
Ionospheric Imprint to LOFAR Norbert Jakowski Institute of Communications und Navigation German Aerospace Center Kalkhorstweg 53, D-17235 Neustrelitz, Germany LOFAR Workshop, 8/9 November 2010, Potsdam,
More informationReading 28 PROPAGATION THE IONOSPHERE
Reading 28 Ron Bertrand VK2DQ http://www.radioelectronicschool.com PROPAGATION THE IONOSPHERE The ionosphere is a region of the upper atmosphere extending from a height of about 60 km to greater than 500
More informationModeling the ionospheric response to the 28 October 2003 solar flare due to coupling with the thermosphere
RADIO SCIENCE, VOL. 44,, doi:10.1029/2008rs004081, 2009 Modeling the ionospheric response to the 28 October 2003 solar flare due to coupling with the thermosphere David J. Pawlowski 1 and Aaron J. Ridley
More informationDaytime Mid-Latitude D-region Parameters at Solar Minimum from Short Path VLF Phase and Amplitude
1 Daytime Mid-Latitude D-region Parameters at Solar Minimum from Short Path VLF Phase and Amplitude Neil R. Thomson Physics Department, University of Otago, Dunedin, New Zealand Mark A. Clilverd British
More informationSpatial and Temporal Variations of GPS-Derived TEC over Malaysia from 2003 to 2009
Spatial and Temporal Variations of GPS-Derived TEC over Malaysia from 2003 to 2009 Leong, S. K., Musa, T. A. & Abdullah, K. A. UTM-GNSS & Geodynamics Research Group, Infocomm Research Alliance, Faculty
More informationRadio Astronomy for Amateurs. Presented by Keith Payea AG6CI
Radio Astronomy for Amateurs Presented by Keith Payea AG6CI Outline Radio Astronomy Basics: What, How, Why How Amateurs can participate and contribute What is Radio Astronomy? The Study of the non-visible
More information2. REPORT TYPE Final Technical Report
REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions,
More informationSpace weather effects on the low latitude D-region ionosphere during solar minimum
Kumar and Kumar Earth, Planets and Space 2014, 66:76 FULL PAPER Space weather effects on the low latitude D-region ionosphere during solar minimum Abhikesh Kumar * and Sushil Kumar Open Access Abstract
More informationPrecipitation of Energetic Protons from the Radiation Belts. using Lower Hybrid Waves
Precipitation of Energetic Protons from the Radiation Belts using Lower Hybrid Waves Lower hybrid waves are quasi-electrostatic whistler mode waves whose wave normal direction is very close to the whistler
More informationAnomalous behaviour of very low frequency signals during the earthquake events
Indian Journal of Radio & Space Physics Vol 43, December 2014, pp 333-339 Anomalous behaviour of very low frequency signals during the earthquake events T Madhavi Latha 1,$,*, P Peddi Naidu 2, D N Madhusudhana
More informationMaximum Usable Frequency
Maximum Usable Frequency 15 Frequency (MHz) 10 5 0 Maximum Usable Frequency Usable Frequency Window Lowest Usable Frequency Solar Flare 6 12 18 24 Time (Hours) Radio Blackout Usable Frequency Window Ken
More informationPerturbations of midlatitude subionospheric VLF signals associated with lower ionospheric disturbances during major geomagnetic storms
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111,, doi:10.1029/2005ja011346, 2006 Perturbations of midlatitude subionospheric VLF signals associated with lower ionospheric disturbances during major geomagnetic
More informationEFFECTS OF IONOSPHERIC SMALL-SCALE STRUCTURES ON GNSS
EFFECTS OF IONOSPHERIC SMALL-SCALE STRUCTURES ON GNSS G. Wautelet, S. Lejeune, R. Warnant Royal Meteorological Institute of Belgium, Avenue Circulaire 3 B-8 Brussels (Belgium) e-mail: gilles.wautelet@oma.be
More informationThe low latitude ionospheric effects of the April 2000 magnetic storm near the longitude 120 E
Earth Planets Space, 56, 67 612, 24 The low latitude ionospheric effects of the April 2 magnetic storm near the longitude 12 E Libo Liu 1, Weixing Wan 1,C.C.Lee 2, Baiqi Ning 1, and J. Y. Liu 2 1 Institute
More informationGPS Ray Tracing to Show the Effect of Ionospheric Horizontal Gradeint to L 1 and L 2 at Ionospheric Pierce Point
Proceeding of the 2009 International Conference on Space Science and Communication 26-27 October 2009, Port Dickson, Negeri Sembilan, Malaysia GPS Ray Tracing to Show the Effect of Ionospheric Horizontal
More informationSPATIAL AND TEMPORAL IONOSPHERIC MONITORING USING BROADBAND SFERIC MEASUREMENTS
SPATIAL AND TEMPORAL IONOSPHERIC MONITORING USING BROADBAND SFERIC MEASUREMENTS A Thesis Presented to The Academic Faculty by Jackson C. McCormick In Partial Fulfillment of the Requirements for the Degree
More informationModeling of Ionospheric Refraction of UHF Radar Signals at High Latitudes
Modeling of Ionospheric Refraction of UHF Radar Signals at High Latitudes Brenton Watkins Geophysical Institute University of Alaska Fairbanks USA watkins@gi.alaska.edu Sergei Maurits and Anton Kulchitsky
More information3C5 Telecommunications. what do radios look like? mobile phones. Linda Doyle CTVR The Telecommunications Research Centre
3C5 Telecommunications what do radios look like? Linda Doyle CTVR The Telecommunications Research Centre ledoyle@tcd.ie Oriel/Dunlop House 2009 mobile phones talk is cheap.. bluetooth 3G WLAN/802.11 GSM
More informationPropagation Tool.
Propagation Propagation Tool http://www.hamqsl.com/solar.html The Ionosphere is made up of several layers at varying heights above the ground: The lowest level is the D Layer (37 to 56 miles), which
More informationELECTROMAGNETIC PROPAGATION (ALT, TEC)
ELECTROMAGNETIC PROPAGATION (ALT, TEC) N. Picot CNES, 18 Av Ed Belin, 31401 Toulouse, France Email : Nicolas.Picot@cnes.fr ABSTRACT For electromagnetic propagation, the ionosphere plays a key role. This
More informationExperimental Weak Radio Signals Monitor for Ionospheric Disturbances Analysis
Programmefor Research-Development-Innovation for Space Technology and Advanced Research - STAR Experimental Weak Radio Signals Monitor for Ionospheric Disturbances Analysis RAMA Presenter: Paul DOLEA,
More informationNighttime D-region equivalent electron density determined from tweek sferics observed in the South Pacific Region
Earth Planets Space, 61, 905 911, 2009 Nighttime D-region equivalent electron density determined from tweek sferics observed in the South Pacific Region Sushil Kumar 1, Anil Deo 2, and V. Ramachandran
More information